1. Field of the Invention
The invention is directed from improved fuel injection device for an internal combustion engine and more particularly to such a fuel injection device having a fuel pump and fuel injection valve comprising a structural unit for each engine cylinder.
2. Description of the Prior Art
A fuel injection device of this kind has been disclosed by EP 0 823 549 A. For each cylinder of the internal combustion engine, this fuel injection device has a fuel pump and a fuel injection valve, which comprise a single structural unit. The fuel pump has a pump piston, which is driven in a stroke motion by the engine and delimits a pump working chamber. A first electrically actuated control valve is provided, which controls a connection of the pump working chamber to a discharge chamber. The fuel injection valve has an injection valve member, which controls at least one injection opening and which, through the pressure prevailing in a pressure chamber connected to the pump working chamber, can be moved in the opening direction, counter to a closing force. A second electrically actuated control valve is provided, which controls the pressure prevailing in a control pressure chamber of the fuel injection valve and which acts at least indirectly on the injection valve member in the closing direction. The second control valve controls a connection of the control pressure chamber to the pump working chamber. This fuel injection device permits a preinjection of a small fuel quantity, a main injection of a large fuel quantity, and a secondary injection of a small fuel quantity to be produced in sequence in an injection cycle. A shared actuator in the form of an electromagnet actuates both control valves. In order for this to be possible, the two valves must be disposed axially in relation to each other, which gives the structural unit comprising the fuel pump and fuel injection valve a large overall height.
The fuel injection device according to the invention has the advantage over the prior art that the two control valves can be arbitrarily positioned, for example next to each other, so that the structural unit comprising the fuel pump and the fuel injection valve only has a small overall height.
Other advantageous embodiments and improvements of the fuel injection device according to the invention are disclosed including an embodiment which permits a fuel injection that has a stepped pressure increase.